Underclocking a baseband chip creates a stealth wifi channel

CNLohr discovered that underclocking the ESP8266 wifi module's Baseband PLL made the wifi channel progressively narrower, until it could not longer be detected by an unmodified wifi receiver -- but a similarly modified wifi module can detect the narrow signal, creating a s00p3r s33kr1t wifi channel; here's sourcecode (which may violate FCC Part 15 rules, so please use responsibly). (via Four Short Links)